js中Array.forEach跳出循环的方法实例

    var arr = [1, 3, 5, 13, 2];
    var res = arr.forEach(function(item,index) {
        console.log(`数组第${index+1}个元素是${item}`);
    })
    console.log(res);//forEach的返回值为undefined,

 try {
   let array = [1, 2, 3, 4]
   array.forEach((item, index) => {
     if (item === 3) {
       throw new Error('end')//报错，就跳出循环
     } else {
       console.log(item)
     }
   })
 } catch (e) {
 }

let array = [1, 2, 3, 4]
array.every((item, index) => {
  if (item === 3) {
    return true
  } else {
    console.log(item)
  }
})

//可跳出循环的数组遍历
Array.prototype.loop = function(cbk) {
  //判断当前数组是否为空
  if (this?.length) {
    for (let i = 0; i < this.length; i++) {
      let stop = cbk(this[i], i, this)
      //判断是否停止循环
      if (stop) {
        break
      }
    }
  }
}


let array = [1, 2, 3, 4]
array.loop ((item, index) => {
  if (item === 3) {
    return true
  } else {
    console.log(item)
  }
})